I’m certain it is lf tag because I was able to copy the fob to T5577 tag by using lf command mentioned here
Are we sure they are LF?
What is RDC?
Could put an RDC up to the reader to check frequency.
Fob is pretty opaque, I tired to put flash light behind the fob to check the chip but I can’t see anything.
Anyone shine a light through the silicone looking encapsulation of that purple fob?