Effective from 1 April 2023 (last weekend) Thailand has reinstated the former Visa on Arrival scheme for tourists from 60 countries. In consequence this will mean that the 45 days visa will be reduced to the original 30 days tourist visa on arrival for the following countries and regions: Europe, the UK, the US, Australia, Saudi Arabia and other countries. Tourists from some countries may need to apply for a formal visa from a Thai embassy beforehand.
Other restrictions are imposed as well incl. so called visa-runs. Therefore always check with your local Royal Thai Embassy/Consulate before travelling.
Source: Thai News PRD.