I have read that many certain year Expedition's LED passenger side strips lost the bottom half of the strip.
When I purchased my 2019, the bottom half of the passenger side strip was burnt out. I made them replace it before I would purchase it.
I don't see any easy way or possibly any way to replace just the strip. And man is the assembly expensive. I now keep mine off in running mode, because I think they burn out from too much use.
I keep mine off in DRL mode also. I have seen that the following part is the piece that can fix it. I have only ever seen the driver side on ebay for around 50-100. I check occasionally for a passenger if it ever gets posted i will snag it. Probably could find one at a pull apart or used light assembly on ebay.
H40376 2018-2021 Ford Expedition Headlight LED Ballast Module