I've said all along, initiating a sizable floor would help most players by a lot more than making the lux tax much harsher.
I get your point about teams facing tax issues not signing even lower level free agents, and I agree, it does affect their eventual deals, but it's hard to say by how much.
Raising the floor to even $90M would add a lot of capital to the free agent and extensions market. According to Spotrac, 10 MLB teams spent under $76M, last season- 4 under $56M.
If you raised it to $125M, teams like these would have to add this much from 2021:
$96M CLE & BAL
$91M PIT
$70M MIA
$59M AX
$54M SEA. OAK & MN
$53M KC
$50M TBR
$35M COL
$33M WSH
$27M Cubs
5 other teams between $22M and 11M.
That's a lot of money- most likely going towards lower tier FAs not the high end one, which IMO, are more in number. This might increase the arb figures more than some few guys making $30M.