There are several versions of a classic "evidence pyramid" that put retrospective studies much lower than prospective ones.*
If you've like a current example, here's a new ESMO (European Society for Medical Oncology) consensus paper, Trapani et al, that carefully puts "retrospective" data at the bottom of a four-level ranking. Trapani, Annals of Oncology, Risk-adapted modulation through de-intensification of cancer treatments." Trapani fig. 1:
Find it here: https://www.annalsofoncology.org/article/S0923-7534(22)00669-X/fulltext
_____
* I've always been annoyed by calling these "levels of evidence" since they're only one aspect of that. An RCT can have a lot of bias, bad endpoints, etc, and shouldn't automatically be ranked on top as "high level of evidence." Then, there are other types of data where a prospective and retrospective study are intrinsically identical to each other in terms of data (such as observational one year transplant survival when you have the whole cohort and each is followed-up to 1 year.)
