Which project? Does the Event Log contain lines commencing "Resent lost task ..." for the download event?

Set preference "Don't use GPU" at the project.

Yes I've done that as a workaround.

That's not a workaround, that is the way to do it. Appointing hardware resources is a project preference, so you set this preference via the projects web pages, all of them and if that's a bother, you use an account manager.

Vitalii is correct in your ticket #4623 that the local client doesn't know if the GPU is going to be disabled forever or not, that's a decision you make and so you should communicate it correctly to the client.

In your opening post, you say that you are pausing GPU work "to save power". That sounds like a long term decision - not just a five minute tea break while you have a quick game of solitaire.

In which case, you could consider excluding the Milky Way project from your GPU(s) in cc_config.xml

If your boss tells you to take some leave because you look tired, you don't go hunting for more work to add to your pile, causing the clients to have an unknown delay.

But your boss will still pile up some work for you to do when you come back. Because this is your specialty.

If you do not want your boss (== the project) to pile up work that only you can do, you tell him you're not available (== at project preferences, uncheck use of GPU).

In your opening post, you say that you are pausing GPU work "to save power". That sounds like a long term decision - not just a five minute tea break while you have a quick game of solitaire.

In which case, you could consider excluding the Milky Way project from your GPU(s) in cc_config.xml

Just encountered a similar problem, but for CPUs. If I only allow work from projects which have "no CPU work" set on the server, it will still request it as a last resort. Perhaps that's useful, if the project you want CPU work from runs out temporarily. But what happens with me is I'm in the middle of allowing new work from different projects, and it grabs what I didn't want before I've turned on the other project.

Do you have”If there is no work available for the project(s) I have selected above, please send me work from another project.” (as an example, this from WCG) ticked?

I wonder if the suspend option, is only meant as to temporarily disable the GPU.
Hence, the work is downloaded anyway.
Disable the GPU is more of a permanent solution.
But I get what you're saying, even with suspend, no new GPU tasks should be downloaded.

From the log you posted at GitHub:

590 Einstein@Home 17-02-2022 10:24 PM [sched_op] Starting scheduler request
591 Einstein@Home 17-02-2022 10:24 PM Sending scheduler request: To fetch work.
592 Einstein@Home 17-02-2022 10:24 PM Requesting new tasks for CPU
593 Einstein@Home 17-02-2022 10:24 PM [sched_op] CPU work request: 757459.98 seconds; 7.00 devices
594 Einstein@Home 17-02-2022 10:24 PM [sched_op] AMD/ATI GPU work request: 0.00 seconds; 0.00 devices
595 Einstein@Home 17-02-2022 10:24 PM Scheduler request completed: got 7 new tasks

You asked, you got. That's how Einstein works.

Did you follow the advice you've been given in #4624? In the context of that issue, Einstein is running a very old server - the base version reports 611, so they won't have the patch that appears to have been applied between 713 and 717

You, or at least your computer requested a pile of CPU work:

591 Einstein@Home 17-02-2022 10:24 PM Sending scheduler request: To fetch work.
592 Einstein@Home 17-02-2022 10:24 PM Requesting new tasks for CPU

It would appear that you are using your local set of preferences and not those held by Einstein, and so you made a call which the server obeyed.

As Richard then pointed out Einstein are running an old version of the server software, and not the current one. BOINC (the project) has no control over what version of code the projects run, so your best line of attack would be to go through the Einstein forum and push them to update to the current server code.
On the other hand, somewhere you say you are using an account manager, are you sure that is doing what you desire?

Einstein has some extra Project preferences which may interfere here:

Of course there's: "Run only the selected applications"
With options:

Run only the selected applications
Binary Radio Pulsar Search (Arecibo)
Binary Radio Pulsar Search (Arecibo, GPU)
Gamma-ray pulsar binary search #1
Gamma-ray pulsar search #5
Gamma-ray pulsar binary search #1 (GPU)
Gravitational Wave search O2 Multi-Directional
Gravitational Wave search O2 Multi-Directional GPU
Gravitational Wave search O3 All-Sky

Then there's these:

Run CPU versions of applications for which GPU versions are available:

Allow non-preferred apps:
If no work for selected applications are available, accept tasks from other applications?

If these are set to Yes, BOINC will happily follow through and ask for CPU work even if "Use CPU?" is set to No. Doesn't matter which server version they sport.
As ever, with running BOINC comes some responsibility from the user, to set all the possible preferences correctly. The client and the server don't (necessarily) know about a CPU or GPU, but they do know about the science applications (through the plan class). And neither cares what hardware resource those applications use.