RAW file showing compression artifacts in LR: same file fine in PS

Photos attached. Image shot raw/.arw with Sony A7RIII. Viewing the photo in LR, at 100%, there are artifacts, they remind me of jpg artifacts--see around the letters. From LR, I opened image in PS (right-click on image, select edit in PS). In PS at 100% it looks fine, I don't see the artifacts. Any idea what's going on?

I tried rebuilding 1:1 preview, quitting/restarting LR, and converting file from .arw to .dng, but issue persists.

LR Classic 9.2.1, PS 21.1.2. Mac OS 10.15.5. 2019 Macbook Pro.