There are two identified issues introduced in version 7.156.0 of the sfdx-cli. Each issue does not exist when using version 7.155.1 or prior, meaning you can install a prior version of the CLI (7.155.1, for example) and not see the issue mentioned.
When using 7.156.0 or greater of the sfdx-cli, REST deploy is no longer working.
Expected
➜ SFDX_REST_DEPLOY=true sfdx force:source:push
*** Pushing v55.0 metadata with REST API v54.0 connection ***Actual
➜ SFDX_REST_DEPLOY=true sfdx force:source:push
*** Pushing with SOAP API v55.0 ***Prior to version 7.156.0, if there was a .forceignore file in a subdirector of the project root where sfdx commands are run, it was ignored, and the one at the root was used.
After version 7.156.0, it appears that the .forceigore files in subdirectories take precedence, and the one at the root is ignore completely.
Expected
When pushing this project's source to the scratch org, nothing is pushed - because it is ignored at the project root's .forceignore.
Actual
The permission set is pushed to the scratch org.