Images blurry when moving slider to edit in Lightroom

Ah see:

https://community.adobe.com/t5/lightroom-classic-discussions/denoise-stopped-working/m-p/14092087

Your GPU unsupported and this other members GPU unsupported, similar although your issue odd blurring on your monitor when adjusting, other members an issue with AI Denoise.

Try the above before trying the preferences file.

Graphics Processor Info:
Init State: GPU Unsupported
User Preference: Auto

May need a MACOS using member to comment. I would think that the M1 in your MAC would work. Apparently a GPU hardware, or GPU driver, or a LrC setup issue. Some MACOS issues involving the GPU driver have shown up and can be seen in Discussions or Bugs, but not that I remember with Apple Silicone, but with AMD GPU's. Also as your MACOS is latest, I would think any Apple Silicone driver issue would be resolved.

Fairly sure an Adobe tech support document exists on GPU issues and some possible fix's (basically based around a corrupt reading by LrC of the GPU). Ah a Camera Raw GPU Config.txt file.(deleting this file with LrC closed, then restarting LrC should recreate it)

• https://helpx.adobe.com/lightroom-classic/kb/troubleshoot-gpu.html
• https://helpx.adobe.com/lightroom-classic/kb/lightroom-gpu-faq.html

And I suspect many will recommend seeing if resetting the LrC preferences file will help. 

The LrC preference file, an actual file, can get corrupted, leading to all sorts of issues. Mind you, this might be seen as a magic bullet, and it might not be the issue. And be aware that resetting ((a.k.a deleting) the preferences file will reset many if not all preference settings to defaults. Note that I am not saying that a particular setting is at fault, but the preference file is corrupt (it has all sorts of bits and pieces it controls). Deleting the LrC preference file (two ways to do that) then restarting LrC should result in a new preference file being created(upgrades, updates, and app uninstall/reinstalls do not)

• https://www.lightroomqueen.com/how-do-i-reset-lightrooms-preferences/
• https://helpx.adobe.com/lightroom-classic/help/reset-preferences.html

By the way, should you attempt resetting the preference file, a recent issue a member had post reset was with presets. If you turn on the option to store presets with catalog, that LrC knowledge of where the presets are will get royally fouled up. Easily fixed if you know before hand that your presets may need to be fixed. just saying.

Watching your video I see contrast changes, I see brightness changes, I do not see focus changes.

P.S. not your described issue, but in your screenshot of LrC /Preferences/Performance/ you have the default value of 5 GB fir the amount to allow the Camera RAW CACHE to occur as a max. Even Adobe states that 5 GB is too small and to increase it to at least 20 GB. (why they do not change the default is a mystery). This WILL effect Develop Module performance ( it will not effect Library Module performance). And the larger your originals are and more pointedly the larger your editing workflow is (number of photos to edit during a session) the worse it will get.

• https://helpx.adobe.com/lightroom-classic/kb/optimize-performance-lightroom.html

Additional observation,

Mac Book Pro M1 

perhaps a MACOS member can assist/comment

Why does your GPU not show up in LrC /Preferences/Performance/ even when use of the GPU is turned off? And are you having additional issues if you turn that on?

Please post your System Information as Lightroom Classic (LrC) reports it. In LrC click on Help, then System Info, then Copy. Paste that information into a reply. Please present all information from first line down to and including Plug-in Info. Info after Plug-in info can be cut out as that is just so much dead space to us non-Techs and it takes up vast amounts of scroll space making the reply less readable and less likely that others will bother with your post. Also large amounts of text in a post also render the Translate function inoperable.