I don't use dryer sheets in the dryer as my repair men have said they shorten the life of your dryer and make them easier to catch on fire.
My mom used Wisk years ago to get red dye out of a rw&b dress that had bled. Recommended to her by the dry cleaning customer she cut her hair on a regular basis and shared their 'secret'.

Use whatever you would use to remove candle wax

Moisten the stain and rub with a bar of Fels Naptha soap takes out even old stains.

Would vinegar work?

I would use rubbing alcohol on it. Test first but it shouldn't hurt the fabric. It will remove tree sap wonderfully and nothing is stickier or ucky as tree sap. If you can find 70% or 91% if you can find it.

I use Dawn and Awesome for stain removal...

I finally gave up and covered the stains.....with birds and whales!

WOW! That's beautiful!!!

Some fabrics just simply do not like dryer sheets. I made a dress from polyester fabric (many years ago). The theme for the dress was supposed to be Southern Belle. By the time I finished the dress, it had become -- well, it just needed to be washed. So, I washed it, put it in the dryer with dryer sheets, and it came out spotted all over. I washed that dress 3 times -- the stains would come out, but I kept using the dryer sheets to dry it because of static electricity, and every time, it came out with spots. I used a can and a half of Shout -- took out those spots every time, and every time I washed it, I put it in the dryer, but the last washing, I did not use dryer sheets -- spots were gone! So, I never used dryer sheets again!

Weighing on on the dryer sheet buzz, I don't use them at all! They will leave stains in all kinds of clothes. They are full of chemicals which stay in your clothes and then you absorb them when you wear the clothes. Not a fan! I recommend not using them at all.