Imo, it is a sign of corrosion in the bulb socket, or the relay, both of which are common...sometimes, a new bulb will give you time. Both bulb change/socket cleaning, and a relay R&R are a slight PIA due to 'room' to work.
There is a DIY here in How Tos, Online Refs, or...
Fwiw, I changed a bulb, cleaned socket and got another few months out of it. Then, back to fast blink. Had the Indy change out the relay when I was getting other stuff done. Not hard, but I watched,
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GL, mD