Do I need a Forsythia reboot?

Before ripping them out, I'd try a major trim back. Start with a "haircut" now... trimming out dead branches, topping the bushes,etc. and keep a clipper with you when you go out to visit them. Clip as you see fit over the summer and Fall. Then in the late Fall, when they go dormant, trim them back as far as you want... to the ground if necessary. The next Spring you should have beautiful new growth on your old stubs. Make sure to compost well and cut a few bare branches in the winter to bloom indoors in a vase. Love, love love forsythia!

Any flowering shrub has to be trimmed right after it blooms, because they set buds for the following bloom season over the late spring and summer. Maybe you are trimming them at the wrong time? Maybe they need fertilizer?

If they have finsished flowering cut them back,allow to adjust and leave. Next season whether permitting give them a bloom booster fertilizer.

Flowers bloom on the previous years growth on forsythia bushes. After the bushes bloom (or in your case, after the neighbors bushes bloom), cut it back then. I have takeb them down to about 6" tall, and the look great the next season. Also, trim out old growth. Those branches will be grayish in color. Give them some tree and bush fertilizer and your forsythia should look great next spring!