It might have something with how you learn, practice and memorise songs.
If you just try to memorise one note at a time it will be harder to remember a song than if you have a solid understanding of music theory and can see why the song is written the way it is. If you can see a musical phrase as a pattern in a scale or as a part of the underlying harmony it will be much easier to remember.
Gerald Klickstein the author of the book "The muscians way" (recommended reading by the way) likes to use 5 zones in practicing.
- New material
- Developing material
- Performance material
- Technique
- Musicianship
https://www.musiciansway.com/blog/2017/12/the-5-practice-zones/
By working really slow in the first two zones and really gaining an understanding of the material you will probably be able to remember song easier.