Does changing old worn out tyre with a new tyre, cause bicycle to move slow and cause gear slip issue??

I have been having gear slip issue between the 4-5th and 7th-8th gear on BTWIN riverside 500 bicycle for quite some time and also the rear tyre over has lost its grip so it got it replaced it with a KENDA K189 700x38c tyre which has similar spec as stock BTWIN tyre. post replacement of tyre, i could sense tightness when i pedal and movement being slow while riding. i got it checked from the nearby decathlon store and got to know that the chain has elongated and that when moving over the cassette is causing the slip.

Need your opinions and expertise on the below.

1. What is the average life of a cassette and chain if used around 10km/day or 40-50km/week. how long do the components last keeping in mind the average usage.

2. I purchased the bicycle in December 2020, during the covid lock down and have extensively used it for about 3000KM as of Aug'24. In this span, i have already changed the cassette and chain once in 2022. this would be the second time.

3. Basis the second point, should i go with the same components from decathlon or can but similar spec components from outside for better life.

4. The stock drivetrain in the bicycle is (9 indexed speeds, B'Twin by Microshift SL759 shifters. Microshift H090 9-speed cassette. KMC X9 chain with quick release. Rear derailleur: B'Twin by Microshift RD M46-L. Chainring: 36 teeth Cogs: 11 / 36. Anti-derailment ring mount. and the one i am trying to replace the same is with Shimano CS-HG200 9-Speed Cassette and KMC X9 Chain – Silver/Grey

Link to the components

Bicycle: BTWIN Riverside 500

https://www.decathlon.in/p/8389412/hybrid-india/adult-hybrid-cycle-riverside-500-grey-red?id=8389412&type=p

replacement component detail

Cassette: https://www.cyclop.in/products/shimano-cs-hg200-9-speed-cassette

Chain: https://www.cyclop.in/products/kmc-x9-chain-silver-grey