Follow up posted to the International Group I'm in ... hence the bias here:

As from 21st June 2025, Paddington Station will NO LONGER be served by bus route 205 to Euston, St Pancras International, Kings Cross and Liverpool Street. This bus route has been my personal recommendation for passengers arriving in London from the West Country, Bristol, South Wales and the Cotswolds carrying on to Eurostar services to France, Belgium and The Netherlands.
There is no suggested bus alternative. Bus route 46 does run from Paddington to St Pancras, but takes you a very long route through North London and takes nearly an hour for the journey. The London Underground Circle line, and Hammersmith and Ciry lines, both run from Paddington (Platform 16) taking between 12 and 15 minutes to Kings Cross St Pancras. None of these direct journeys are included on the Interrail / Eurail pass.
You can use your Interrrail / Eurail Pass from Paddington (platform A - entrance from near platform 1) to Farringdon on the Elizabeth line, and change there onto a northbound Thameslink train from platform 4 to St Pancras.
The 205 was a very useful way for those with heavy luggage and in wheelchairs / with limited mobilty to get from trains from the West of London to International services from St Pancras and services for North East of London.
An article in The Standard alerted me to news of the change and told of consultations with local residents. It acknoeldged that the change is an unpopular one, but told us that the change has been made for cost and efficiency reasons, promising a better service on the remains of the route which - however - does not serve Paddington. No mention is made in the article of consultation with long distance / limited mobility customers for whom this was the best cross-London option