The UK is working on a separate data protection law and the attitude towards privacy is very different from the EU (hence the rewrite)
And post Brexit they'll ignore all the CJEU case law about how blatantly companies have been building GDPR since the start.
[1] https://uk.practicallaw.thomsonreuters.com/w-026-8528?contex...
[2] https://www.gov.uk/government/consultations/data-a-new-direc...
This is very speculative. My guess is that changes will be made, but they'll be incremental and some effort will be made to ensure broad alignment with eu GDPR so we don't have another SCC-syle mess (where some major EU to USA data transfers were determined to be illegal.)
*I get a GDPR-looking privacy popup on Threads in the UK so I'm inclined to agree