What are the current options and limitations for border visa runs from Bangkok for Canadians in 2022?

There's no such thing as a border visa run. You either do a border run (go to the border, stamp out of Thailand, into another country, then turn around and come back to Thailand), or a visa run (go to a Thai consulate in another country and apply for and purchase a visa).

Normally a border run is to use a visa exempt entry, or get another entry on a multi-entry visa you already have.

The rules have also not changed regarding this and have been the same for a long time.

There is no written rule that limits how many visas you can get in a year or how many times you can enter with a visa in a year. It's all at the discretion of the embassy/consulate or passport control officer.

The only written limitation is a maximum of 2 land entries, by visa exempt, per calendar year. You can enter an unlimited number of times visa exempt by air, once again at passport control officer discretion. This rule was in place before Covid ever happened.