You have what is known as dye transfer.
Dye Transfer is the dyestuff transferred to leather from clothing, newsprint or from hair dyes and fake tans. It is more usually seen on light coloured, protected, leathers but it can occur on any leather, though not as noticeably. Basically the dye has redyed the leather. It is a very common problem.
First check the type of leather you have. Dye transfer can generally be used safely on pigment coated leather but not always from Aniline style leather. Dye transfer removal products should not be used on Aniline leather and it is best to take expert advice before any attempt is made. Auto leather is generally pigment coated but it is worth checking.
If noticed early enough it can be successfully removed from most pigment coated leather with a Jean and Dye Transfer Removal Kit. This contains specifically formulated (by leather technologists) products for this problem. If this cleaning process does not resolve the problem it will be necessary to call in an experienced technician as early as possible. The longer the dye sits in/on the leather the harder it will be to remove.
Using a good quality Leather Protector will help to inhibit dye transfer as the dye will sit on the protector and not on the finish of the leather. This also makes it much easier to clean off. Conditioners will not do this and should not be used.
Owners of pale and off-white leather are recommended to adopt a gentle regular cleaning and protecting regime using good quality maintenance and protection products (not conditioners as these actually attract more dirt) Please do not use anything containing waxes or oils on your leather as these will not help and polishes may seal the surface and prevent further cleaning.
Please do not use Magic Erasers to clean leather as these are a very fine sand paper and will damage the finish on the leather causing long term problems.
Products sold in furniture stores and supermarkets are not generally strong enough products to really protect leather from this problem or to clean the dye transfer once it has happened.
Always take expert advice when dealing with leather as they will help you avoid expensive problems.
Please do not use saddle soap which is meant for saddles and not the type of leather you have. It is too harsh for modern leather finishes and could damage the leather.
Hope this helps
Judyb