With your 1st vote, you vote for a CANDIDATE in your single-member district; & vote for a PARTY LIST with your 2nd.
Since Plaid Cymru will probably win a majority of seats with 1st votes, it won't top up extra seats via the 2nd, meaning that voting PC/PC would be wasting your 2n...
Bluesky post by @grumpyoldleftygit.bsky.social