Weird, if it's not the capacitor, either your arduino or psu is fu..ed up. There are many options to have problems with these strips but they are all related to either voltage drop because of too tiny/too long wires, or too big voltage difference between signal and power (common in 3.3v signal from MCU) or interferences on signal wire. But those would cause problems independently if you connect the strip at startup or later. Try with another power adapter. Safety is always important, but consider that powering a led strip with cheap cinese adapter is much more safe than charging your cell phone with that (presence of battery). Also, in residential use, no one runs a strip with all leds on at full power, it's like having 180 cell phone camera flashes on at the same time... I don't know your use case but if you are looking for light effects like most of us, you probably get enough juice from your old reliable iphone or samsung charger.
Don't underestimate these. They work quite well for the most part.
If you have a scope, you could have a look at the startup behavior and transient response of the problematic power supply. I expect that would yield some clues. But frankly, I wouldn't waste too much time on this; just put a sticker on this unit so you remember something's up with it next time you rummage through the parts bin, and get a decent replacement for this project.
@rsmls thanks! I will surely get another PSU for this project
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