I personally think it can be a range of things IMHOI tried applying for Amex Velocity Platinum on Jan25, April25, Aug25 and got rejected for all of them. Applied for Amex Explorer right after my rejection for Amex Velocity Platinum on Aug25, and got approved for 18k limit.
Lower annual fee but also lower bonus points. Earn rate roughly similar but could transfer to more partners. Honestly, don't understand what drives their decision.