[SMHarman]

What kind of cooker is connected to this?

If this is just an electric oven then current wise, this is likely to be safe, but if an electric hob is involved, the this is dangerous.

2.5mm cable is rated to about 20A, but for safety can only be used to carry 16A (or 32A in a ring).

An all electric cooker should be on a 6mm cable which is rated for use at 32A. This must be connected through a proper cooker switch and outlet, and these must be less than 2 m from the cooker.

Somewhere in your kitchen is a junction box (probably the cooker outlet) which has had the 2.5 mm connected to it to power the cooker.

Conclusion if your cooker is all electric some remediation work needs doing, if your cooker is dual fuel (or gas requiring electric for the spark and clock) you need to establish if that cable has a 13A fuse on it, or change the MCB for a 16A one.

For completeness, other cables you will find around the house are 1mm or 1.5mm which is for lighting, Lighting circuits are usually 6A. and 10mm which is rated to 46A and for electric showers of over 7KW.