Covid restrictions around the world are lifting, but as the world comes out of the pandemic, rules are different around the world. The best way to check you adhere to the latest regulations in the country you are visiting is by checking with your government's foreign office or equivalent.
United Kingdom: https://www.gov.uk/foreign-travel-advice
United States: https://travel.state.gov/content/travel/en/traveladvisories/traveladvisories.html/
Germany: https://www.auswaertiges-amt.de/de
Netherlands: https://www.rijksoverheid.nl/
France: https://www.diplomatie.gouv.fr/fr/
Spain: https://www.exteriores.gob.es/en/Paginas/index.aspx
Ireland: https://www.dfa.ie/