Google is upgrading its conversion models beginning in May 2023. They announced that four attribution models would be removed from Google Ads as well as Google Analytics.
Google Conversion Models
The 4 attribution models that Google intends to remove are (First click, Linear, Time Decay and Position-Based) as announced by Google Ads liaison Ginny Marvin.
Less than three percent of all Google web conversions are made using any of the four models that have been discontinued.