Plenty of ways that someone's ID can be known.
Shop owners get to identify punters through their reviews. Not uncommon for a shop owner to ask you to do a favorable review (ID then known ... bingo).
They could ask you to modify an unfavourable review.
They could ask you to delete or change a review with too much detail.
They could ask you not to review as they don't want the attention.
... so definitely shop owners can know some IDs.
Some punters appear to have "arrangements" to be first in with new girls etc ... then they write a "nice" review.

Some MLs know punters IDs. Happens for various reasons. Especially if the shop owner knows the ID as "comms line" is often shared.
MLs can tell others of your ID. Like telling a shop owner.
Who knows how far that goes.

Some punters may get together ... hence know each other and their ID. Does happen.
Some punters can have multiple IDs. I only have one.
Some people get to know quite a lot about other punters through reviews, DMs and gossip.