Hello, and welcome to the forum.
I would suggest that one of the indicator bulbs on the left is "on the blink". If one of your bulbs is dead or on the way out the indicators on that side blink faster. It could be that there is also some corrosion in one (or both) of the bulb sockets, causing a poor earth connection. Check the indicators, and replace the offending bulb, but check the socket, just in case. Good luck!