2021.03.01 16:29 "[Tiff] TIFF and multispectral images of historical documents?", by Andreas Romeyke

2021.03.02 19:07 "Re: [Tiff] [Off Topic] TIFF trademark", by Scott Ribe

There is no mention of a TIFF trademark.

Indeed, a few minutes with uspto.gov seems to confirm that Adobe never trademarked it.