The Quarantined Domains extension blocks non-Recommended extensions on selected sites. It's interesting to see what sites are "protected" from user add-ons in Firefox 115:
Preference name: extensions.quarantinedDomains.list
Preference value: autoatendimento.bb.com.br, ibpf.sicredi.com.br, ibpj.sicredi.com.br, internetbanking.caixa.gov.br, www.ib12.bradesco.com.br, www2.bancobrasil.com.br
The fact that these are all financial institutions in Brazil makes me wonder whether Mozilla is doing this to manage some potential legal liability around use of Firefox add-ons on those sites. Maybe some day the full story will come out.