Tear out regular mesh Fiba tape in tub setting?
Long term consequences? Yes. The thinset mortar and the backerboard will release alkali when exposed to moisture and over time that will deteriorate the fiberglass resins in the tape. Major consequence? Meh... the tape is there to reinforce the corners and edges against minor shifting in the house structure so that it doesn't result in straining the mortar, leading to cracks and dislodging of the tiles. If it's a tub area, only the lower areas will likely see enough moisture contact to affect the alkali release, so then the rest of the tape in the corners is still going to aid in keeping it all together. And besides, you may not get a lot of shifting of the structure anyway. Not everyone even uses tape at all!