Question Urgent help needed with misbehaving UPS ?

[Kirito-kun]

My specs
Motherboard: H61
CPU: i5-3570
GPU: RTX 2060
RAM: 2 x 4GB
PSU: 550W Bronze+ CM
2 x SSD, 2 x HDD
RGB Keyboard and Mouse
Bluetooth and WIFI Adapter
Case Fans: 3 x ARGB and 1 x non-RGB
Monitor: Acer 22 inch IPS

I have a inverter at my place but due to frequent power cuts in my area, I bought an
ENTER UPS E-U740 LINE UPS (Output Power Wattage: 360 W) from a local shop to protect my GPU for that 1 minute when the electricity cuts off and switches to Inverter, it provides good backup during normal usage (when GPU is not in use), but whenever I am playing games COD series, GTA V, the moment the electricity goes off my pc crashes and then in next second the inverter kicks in, it restarts.

I thought there was something wrong with my UPS so I took my PC and UPS to the shop, but there it managed to play GTA V, Genshin Impact and COD:MW Remastered for total 4-5 minutes before discharging. I brought it back home, separated Monitor connection directly to board and tested same thing (switched off power connection during Genshin and it survived), I thought it solved the problem but again just 30 mins back , my friend was playing COD:MW and electricity goes off and again PC goes off. This is so much frustrating!!! Please need urgent help!!!

Another point to Note: When I am cutting off the electricity first and starting PC on UPS directly, I am able to run few games (Genshin , COD:MW, GTA V) for few minutes, but whenever I am playing on electricity through UPS, the moment electricity goes off the PC shuts down, the UPS is not providing even a one second backup.