In Photoshop26 v27.8 on MacBookPro M4 OS 15.7.7 the brush tool suddenly started showing a patch of grey squares all around the area the brush is being used. Also happens with clone and healing brushes. Makes PS almost unusable. Please help.

In Photoshop26 v27.8 on MacBookPro M4 OS 15.7.7 the brush tool suddenly started showing a patch of grey squares all around the area the brush is being used. Also happens with clone and healing brushes. I have made sure everyhitg is up to date. I’m using a Wacom tablet, driver is up to date. I’ve restarted everything mutlipe times. Problem is intermittent. Happened yesterday for the first time. This morning it seemed to have resolved, but is back and now happens with clone and healing brushes as well. Making PS almost unusable. I’ve seen a few random solutions including “Preferences > Technology Previews>Deactive Native Canvas” but I don’t see that option. Anyway it’s really slowing me down. Thanks for any help.