The concept involved is referred to as a delimiter.
The software being used must know what character is being used to separate data values.
Rows and fields (columns) within that row/record.
Your sample textfield that works is probably from a source using CSV. Likely
, 1.2.3.4.5 , and interpreted as a single data value. Note the commas.
CSV Comma Separated Value) is one method of separating data fields. So if a comma is used in the data the software will interpret that comma the next data value. Other characters can be used as delimiters but there are rules and restrictions.
So if the data is 1,2,3,4,5 that will interpreted as five different values. Depending on software any values after the first comma may be pushed into other fields or simply be truncated.
Another way of managing incoming data values is fixed format.
Reference (and you can easily find other such links):
https://towardsdatascience.com/parsing-fixed-width-text-files-with-pandas-f1db8f737276
If you are going to be working with lots of data then learning how to parse data of any sort is an important skill to have.
= = = =
There is a dependency on the software being used to import, process, and export the data. Often user configurable - you get to select (within given rules) what delimiter is to be used.
What software are you using?
Do a google search on "how to delimit data" then apply other search criteria and filters as necessary to narrow down the search results that match your software and specific requirements.
Most likely, you can insert quotes around the data if the data values contains commas. However, that has to be planned out in advance via the design process. Again, there are different ways of doing such things.
What software are you using? What is the source and format of the data you are trying to process? What do you have control over?
For example, if you have no control over the data being provided then you must manage the parsing of the data to accommodate data fields that contain commas as part of your processing requirements.
Fortunately, Excel, Access, etc. provide many functions to help solve such problems.