Is a bad Wi-Fi repeater better than no repeater at all?

I got a very cheap gift. Even when you touch it you can feel how cheap it is (ultra light, cheap plastic, …). Since I'm not very familiar with it, I'll upload a picture of the repeater here (maybe someone knows it). On the packaging and on the device itself there's no brand, no serial number (as I know it) and no other information, except for the Mac address (whatever it may be here), the PIN and a sequence of numbers and letters, preceded by "8 / N" stands. I know that every repeater and every router in the vicinity of my Fritzbox 7520 is a source of interference. So I thought about it and asked myself whether it would make sense to connect the repeater to the Frotzbox and thus play with Lan on the Ps4. Trying is better than studying, but I can't judge that very well ^^.

You then get your WLAN from the repeater. This means that if it gives a bad signal, you also get a bad signal

So I bought antennas for my Fritzbox. This gives me full beams throughout the house.

I can only recommend

The question was yes "is a bad Wi-Fi repeater better than no repeater at all", I now don't know what to do with the answer

Does the part have a CE mark and / or a GS mark?

A repeater is not set up near the router, but at the edge of the coverage area. It also doesn't make sense to be too close, as interference could occur.

Then read again

It has a CE and an FCC mark

Not correct. A bad signal just means a low level. As long as the digital content can still be adequately decoded, there's no compromise in data quality.

Nevertheless, the reception is then worse

Of course, the repeater is further away from the router and I place it where it is between my desk and router

It's about the LAN connection and not about the WLAN

This is a "0815" standard N300 repeater, probably 2.4 GHz n-standard with 300 Mbit / s (= two internal antennas).

It often supports 3 operating modes:

WLAN repeater (possibly also WLAN client)
WLAN access point (AP)
WLAN router (actually never needed)

It will create approx. Max. 75 Mbit / s net configured as a WLAN client. As a repeater, maybe 45 Mbit / s.

These things are offered en masse by various manufacturers, often made in China.

Here is an identical one: https://www.real.de/product/355739494/

Basics:

Only use the repeater if the signal strength is too weak
Do not use repeaters in the router's room or in the client's room; this is more annoying than it helps
Repeaters in client mode (= like a WLAN adapter) never interfere, they are only WLAN receivers.
All repeaters are made of plastic, because metal and radio do not get along!
All of these repeaters use standard WLAN chips, which are all similarly good / bad. You have to try it out.

Good or bad? No Wi-Fi reception (without repeater) or normal Wi-Fi reception (with repeater)? This repeater would be fine with me.

PS:

Plug in your LAN cable and call up the configuration page in the browser, it does not need to be connected to WLAN. The PC will report "No internet connected", but you can still go to the repeater's configuration page.
Enter his IP in the browser, after a factory reset it is probably 192.168.10.1 then look for what model it is and google it, then you know more about the manufacturer.