Issues with numbers in product names

[webchills]

If you have many products with numbers in the product name you get weird results with instant search.
Product names with dots and numbers are widespread.

Examples:
GEWA Idea 1.8 Carbon Case
GEWA Idea 2.7 Carbon Case
GEWA Idea 3.1 Carbon Case
and many other products with numbers in the name
e.g.
AKG 1744
Hewlett Packard LaserJet 1100Xi Linked

A search for Idea 1 is delivering lots of other products with a 1 in the name
A search for Idea 2 is delivering lots of other products with a 2 in the name
A search for Idea 3 is delivering lots of other products with a 3 in the name
Depending on the number of other products a customer who is looking for Idea 1.8 or Idea 2.7 or Idea 3.1 gets completely useless results, often the real matching Idea 2 product is not even in the first top ten

You can see the examples live here:
https://instant.webchills.it

This is a vanilla 1.5.8a store
with InstantSearch 4.03
MariaDB 10.6.18
PHP 8.2.20
The product fields are set to the standard:
model-exact,name-description,model-broad,meta-keywords,category,manufacturer
Query Expansion is set to false
Normal config, no Typesense

I tried other product field settings, they have no effect on this problem.

If you disable Instant Search and use the normal in-built search you get only the suitable results.